axi4: an adapter to remove user bits

src/main/scala/uncore/axi4/UserYanker.scala

@@ -0,0 +1,88 @@
+// See LICENSE.SiFive for license details.
+
+package uncore.axi4
+
+import Chisel._
+import chisel3.internal.sourceinfo.SourceInfo
+import config._
+import diplomacy._
+import uncore.tilelink2.UIntToOH1
+
+class AXI4UserYanker(maxFlightPerId: Int)(implicit p: Parameters) extends LazyModule
+{
+  require (maxFlightPerId >= 1)
+
+  val node = AXI4AdapterNode(
+    masterFn = { mp => mp.copy(maxFlight = maxFlightPerId, userBits = 0) },
+    slaveFn = { sp => sp })
+
+  lazy val module = new LazyModuleImp(this) {
+    val io = new Bundle {
+      val in  = node.bundleIn
+      val out = node.bundleOut
+    }
+
+    ((io.in zip io.out) zip (node.edgesIn zip node.edgesOut)) foreach { case ((in, out), (edgeIn, edgeOut)) =>
+      val bits = edgeIn.bundle.userBits
+      val need_bypass = edgeOut.slave.minLatency < 1
+      require (bits > 0) // useless UserYanker!
+
+      val rqueues = Seq.fill(edgeIn.master.endId) { Module(new Queue(UInt(width = bits), maxFlightPerId, flow=need_bypass)) }
+      val wqueues = Seq.fill(edgeIn.master.endId) { Module(new Queue(UInt(width = bits), maxFlightPerId, flow=need_bypass)) }
+
+      val arid = in.ar.bits.id
+      val ar_ready = Vec(rqueues.map(_.io.enq.ready))(arid)
+      in .ar.ready := out.ar.ready && ar_ready
+      out.ar.valid := in .ar.valid && ar_ready
+      out.ar.bits  := in .ar.bits
+
+      val rid = out.r.bits.id
+      val r_valid = Vec(rqueues.map(_.io.deq.valid))(rid)
+      val r_bits = Vec(rqueues.map(_.io.deq.bits))(rid)
+      assert (!out.r.valid || r_valid) // Q must be ready faster than the response
+      in.r <> out.r
+      in.r.bits.user.get := r_bits
+
+      val arsel = UIntToOH(arid, edgeIn.master.endId).toBools
+      val rsel  = UIntToOH(rid,  edgeIn.master.endId).toBools
+      (rqueues zip (arsel zip rsel)) foreach { case (q, (ar, r)) =>
+        q.io.deq.ready := out.r .valid && in .r .ready && r && out.r.bits.last
+        q.io.enq.valid := in .ar.valid && out.ar.ready && ar
+        q.io.enq.bits  := in.ar.bits.user.get
+      }
+
+      val awid = in.aw.bits.id
+      val aw_ready = Vec(wqueues.map(_.io.enq.ready))(awid)
+      in .aw.ready := out.aw.ready && aw_ready
+      out.aw.valid := in .aw.valid && aw_ready
+      out.aw.bits  := in .aw.bits
+
+      val bid = out.b.bits.id
+      val b_valid = Vec(wqueues.map(_.io.deq.valid))(bid)
+      val b_bits = Vec(wqueues.map(_.io.deq.bits))(bid)
+      assert (!out.b.valid || b_valid) // Q must be ready faster than the response
+      in.b <> out.b
+      in.b.bits.user.get := b_bits
+
+      val awsel = UIntToOH(awid, edgeIn.master.endId).toBools
+      val bsel  = UIntToOH(bid,  edgeIn.master.endId).toBools
+      (wqueues zip (awsel zip bsel)) foreach { case (q, (aw, b)) =>
+        q.io.deq.ready := out.b .valid && in .b .ready && b
+        q.io.enq.valid := in .aw.valid && out.aw.ready && aw
+        q.io.enq.bits  := in.aw.bits.user.get
+      }
+
+      out.w <> in.w
+    }
+  }
+}
+
+object AXI4UserYanker
+{
+  // applied to the AXI4 source node; y.node := AXI4UserYanker(idBits, maxFlight)(x.node)
+  def apply(maxFlight: Int)(x: AXI4OutwardNode)(implicit p: Parameters, sourceInfo: SourceInfo): AXI4OutwardNode = {
+    val yanker = LazyModule(new AXI4UserYanker(maxFlight))
+    yanker.node := x
+    yanker.node
+  }
+}